Conventionally, when a defective area exists in a bulk memory disposed as an information storage medium, information about the defective area is stored in a part of the bulk memory, and, when access to the defective area occurs, access to the bulk memory is enabled or disabled with reference to the information.
As such a technology for accessing a bulk memory having defective areas, an information storage method of and an information storage apparatus for enabling stable continuous recording of information in an information storage medium even if many defective areas exist in the information storage medium, and a method of reproducing the information recorded in the information storage medium are known (refer to patent reference 1, for example). In accordance with this technology, information per file is recorded in the information storage medium, and a contiguous data area which is a continuous record area provided for reducing the frequency of access to an optical head and for making it possible to continuously record information in the information storage medium is defined. This contiguous data area is defined so as to extend over either of another file record area which is already recorded in the information storage medium, or a defective area on the information storage medium, and an extent is defined, as an information storage place, with respect to areas divided by the other file record area or the defective area on the information storage medium.
[Patent reference 1] Japanese Patent No. 3376364
By the way, for a bulk memory typified by a related art hard disk, a set of conditions, such as temperature, humidity, and vibrations, under which the manufacturer of the bulk memory guarantees the performance of the bulk memory, i.e., a performance-guaranteed environment is provided. Such a bulk memory has a function (called a smart function) of, when an error occurs while the bulk memory is placed in the performance-guaranteed environment, recording information about the error in a log area which is disposed within the bulk memory. Therefore, a host device connected to the bulk memory can know both the occurrence of any error and the status of the bulk memory when the error occurs by referring to the log area.
However, when the related art bulk memory is used outside the performance-guaranteed environment and an error occurs, any information about the error is not recorded in the log area of the bulk memory. Therefore, when the related art bulk memory is used outside the performance-guaranteed environment and an error occurs, the host device cannot know the fact.
On the other hand, in recent years, bulk memories have come to be adopted by systems, such as car-navigation systems, which are used under severe conditions, so as to provide improvements in the functionality and performance of the systems. In such a related art system, even if the system is placed outside a performance-guaranteed environment, there is a necessity to write data in the bulk memory. Generally, the bulk memory is designed so as to have a certain margin against writing of data when it is placed outside the performance-guaranteed environment, and therefore writing of data into the -bulk memory attains success in most cases even if the bulk memory is placed outside the performance-guaranteed environment.
A problem with the related art system is however that when data are written into the bulk memory which is placed outside the performance-guaranteed environment, if an error occurs, a host device connected to the bulk memory cannot know the occurrence of the error, and therefore cannot grasp whether the bulk memory is operating normally, thereby decreasing the reliability of the system.
The present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide an information storage system that can write data in a bulk memory normally and can increase its reliability even if it is placed outside a performance-guaranteed environment.